Possible technologies for analyzing single molecules (e.g. nucleic acids) include tunneling junction devices that have a sub-molecular sized gap between two electrodes. When the molecule makes contact with the two electrode, the molecule may create a tunneling current. The tunneling current can be analyzed to identify a portion of the molecule. Dimensions of the gap may be on the order of nanometers, including less than 2 nm, or even sub-nanometer. Creating a gap of this size may require precise and expensive techniques. Toolsets and processes for tunnel junctions have been developed by magnetic recording media industry to manufacture magnetic junctions for hard-drives and non-volatile memory devices that are currently under development (W. Zhao, et al., “Failure Analysis in Magnetic Tunnel Junction Nanopillar with Interfacial Perpendicular Magnetic Anisotropy,” Materials, Vol. 9, 41, 2016; P. Tyagi, E. Friebe, and C. Baker, “Advantages of Prefabricated Tunnel Junction-Based Spintronic s Devices,” NANO: Brief Reports and Reviews, Vol. 10, 1530002, 2015).
Devices with such a small gap between electrodes may be subject to device failure, such as electrical shorts. Furthermore, maintaining such a thin layer between two electrodes is difficult. Improvements in the design and manufacturability of tunneling junction devices are still needed, particularly for analyzing single molecules. Ideally, design and manufacturability improvements should not come at the expense of accurate and precise analysis. These and other issues are addressed by the technology described in this document.